Description: A traditional farmhouse design, but a structure built to one of the highest standards of energy efficiency—German Passive House. The key is a tight, super-insulated building envelope that keeps the heat inside. The home is heated and cooled passively by the sun and by earthtube piping buried deep beneath the structure. Green features include double-wall construction, triple-pane windows, solar shading and careful siting. LEED Platinum and Energy Star certifications.